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List:       lustre-discuss
Subject:    Re: [lustre-discuss] Limit client side caching?
From:       Andreas Dilger <adilger () whamcloud ! com>
Date:       2019-05-07 22:52:03
Message-ID: 5489D238-1B3B-4AEF-A905-10DCC7942128 () whamcloud ! com
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On Apr 22, 2019, at 10:35, Nehring, Shane R [LAS] <snehring@iastate.edu> wrote:
> 
> Hello
> 
> Is there a way to limit the client side caches to a specific size?
> We're occasionally seeing panics due to failed allocations in low
> available memory conditions in our environment. We limit user
> allocations with cgroups through slurm, but it would be handy to
> know exactly how much ram to reserve for system use.

You can limit the size of the client cache via the "max_dirty_mb" and "max_cached_mb" \
tunables.

There is an aggregate "max_dirty_mb" for the whole client, which is the total amount \
of unwritten/in-flight dirty data, and a separate "osc.*.max_dirty_mb" tunable \
(per-OST value) if you want to tune the maximum amount of unwritten data differently \
for multiple client mountpoints.

The "llite.*.max_cached_mb" is the amount of cached (dirty+clean) cached data for the \
filesystem.  By default this is 3/4 of RAM.

Cheers, Andreas
--
Andreas Dilger
Principal Lustre Architect
Whamcloud

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